remove the idle mixture screws, make sure the washer and o-ring come out and spray into there. easiest way to clean. yes remove the slides and put some a rag over the opening before u spray.
I’ve done that when the carbs were off the bike. Spray was squirting out of the 3 transition ports in the throats of the carbs. The last time I did it, green laquer colored spray came out of one of the air jets at the carb inlet side when I blew air into it after the spray. Spray came out of others, but I don’t recall it coming strongly out of all of them. I suspect that the air inlet side of the circuit may be blocked or partially blocked between the air jet and where the transition ports are. If this doesn’t work, I’ll pull the carbs again and repeat the cleaning process.